Nice!
I found this while looking for boss battle music to listen to. It's nice and original!
the only problem I had with this song was that it kinda felt unfinished.
I have two suggestions:
1. Remove the last 18 seconds from the song. When I listen to those last few seconds, I think, "OH MY GOSH! IT'S FINALLY OVER!!!" When I realize the song's too short, I am left with a disappointed feeling.
2. Make the song longer and make sure it's still good.